Acceleport RAS4 ringback support?

I’m trying to detect the difference between NO ANSWER and NO CARRIER, as documented in the command reference supplied by Digi. The modem seems to return ‘NO ANSWER’ when there is an answer. I’ve set all the status code options that I could find after scouring the documentation (which I used to select the product for this feature).

Specifically, setting Q0X4S7=10, and using the “hayes” command set, I get nothing beyond “NO ANSWER”. Also, using Fax/Class2 commands, I get no synchronous FHNG responses, just “NO ANSWER”.

I’m dialing outbound on a POTS line into the PSTN. I am manually testing both the ‘answer’ and the ‘no answer’ scenarios. I’ve not been successful in getting any sort of ringback detection to work.

This is a documented feature which I’m concerned is not actually present. I’m hoping I missed something, else I’ll have to look for another board.

Does anybody have a suggestions? Any help is much appreciated.